This invention relates generally to autotransfusion apparatus, and more particularly to improvements in apparatus and procedures for accomplishing such transfusions.
Autologous blood transfusion has become very popular in recent months due to increased concern over transmission of diseases through banked blood. After a total joint replacement such as knee or hip, the wound continues to bleed for several hours. Normally this blood is collected in an evacuated container and discarded. But studies have shown that this blood is of high quality and can be reinfused.
Prior devices to accomplish such transfusions employ flexible bags in rigid outer containers, the container in one position adapted to receive blood from a patient to fill the bag; and in an inverted position of the container the blood drains from the enclosed bag. In a typical procedure, anticoagulant is added to the bag through an injection site in inlet tubing. Great care is taken to keep the bag upright to prevent the liquid anticoagulant from entering the evacuation tube that contains the hydrophobic filter. If this filter chamber gets filled with the liquid during the blood collection process then the unit cannot be evacuated and air in the container cannot be displaced by the incoming blood. The unit is thus rendered inoperative and has to be discarded or the filter has to be replaced.
After blood is collected in the bag, the unit is disconnected from the drain and prepared for re-infusion. To re-infuse the collected blood, any air in the bag is expelled by infusing air into the interstitial space surrounding the bag.
Disadvantages with such prior devices include:
1. The bag has to be kept upright during the entire collection procedure. This is not very easy because the bag has to be handled several times during patient transfer from the operating room to recovery room to floor. With the hydrophobic filter covered in liquid, the unit becomes inoperative and there is no indicator to tell the nurse that the unit has become inoperative.
2. The activation of vacuum requires availability of wall suction with accurate vacuum regulator. If the regulator is set too high, the outer bottle collapses and the unit becomes inoperative. High vacuum could also cause hemolysis of the blood.
3. The flow-through system of evacuation causes an air-blood interface. This can lead to hemolysis.
4. The air in the bag at the end of collection has to be expelled prior to re-infusion. This is an awkward maneuver and sometimes causes blood to squirt out of the bag.
5. The device has no means of indicating the presence of vacuum in the system.
6. The device has no graduations to indicate volume during re-infusion.
7. The device is quite complicated to use, and inadvertent clamping or unclamping of tubes or tipping the unit can lead to malfunctioning of the unit.
There is need for improved apparatus to accomplish such blood transfer.